Our cat used to get really anxious when he saw the suitcase come out as well. Once, he was particularly upset and pee'd in my husband's half-packed suitcase--just to get his point across. I'm not sure what was funnier--the look on my husband's face when he saw what had happened or the look on the cat's face when he saw my husband about to chase after him to scold him. I'm pretty sure the cat won.
Speaking of our pee'ing cat, he usually loves it when we have houseguests over but he doesn't like one particular relative (who's a very nice guy by the way). Our cat will ALWAYS find something of this guy's and pee on it. And yet this guy keeps coming over to our house.